Breathing circuit devices can make breathing air or breathing gas available to a respirator user of the breathing circuit device over a longer period of time. The carbon dioxide is removed from the expiration gas expired by the respirator user by means of a carbon dioxide absorber and oxygen is fed in from an oxygen tank. Breathing gas can thus be made available for the respirator user from a small and compact breathing circuit device with a small volume of pure oxygen in the oxygen tank even for a longer period of time, e.g., four hours.
Breathing lime or alkali, which absorbs the carbon dioxide present in the expiration gas expired by the respirator user, is contained in the carbon dioxide absorber. Moisture and heat are released during this chemical reaction, and this leads to a corresponding heating and humidification of the inspiration gas because the expiration gas expired by the respirator user is again made available as an inspiration gas to the respirator user in a breathing circuit system. This is unacceptable for a physiologically tolerable breathing climate, so that cooling and dehumidification of the expiration gas is necessary after passage through the carbon dioxide absorber. The breathing circuit device is provided for this purpose with a cooling element for cooling and hence also dehumidifying the breathing gas. The expiration gas is cooled by means of the cooling element and cooled to below the dew point in the process, so that the moisture contained in the breathing gas condenses. Various means, for example, water ice, a latent heat storage means or a zeolite cooler, are used as cooling elements.
A cooling device for breathing gas cooling in a respirator with a heat collector exposed to the breathing gas flow is known from DE 40 29 084 A1. The heat collector is designed as a reservoir for an evaporable liquid and can be connected to an evacuable absorbent container, so that the liquid evaporates while absorbing heat of evaporation and its vapor is absorbed on an absorbent present in the absorbent container while heat of absorption and heat of condensation are released, the absorbent container being designed as a cooling body arranged outside the breathing gas flow and intended for releasing heat to the environment.
It is not possible to arrange different cooling elements at the breathing circuit device in the breathing circuit devices known from the state of the art if good heat conduction from the breathing gas to the cooling element is to be guaranteed at the same time. Different cooling elements have different surfaces, so that adaptation to these different surfaces is necessary for good heat conduction from the breathing gas to the cooling element.